Congressional leaders have spent months telling voters that all spending must be on the table, but so far the rhetoric is ringing hollow on Capitol Hill, where defense cuts remain a tough sell.

That was clear last week after Sen. Rand Paul presented his Republican colleagues with military cuts as part of a broader effort to balance the budget within five years.

“I got several fairly vocal objections to it,” the Kentucky Republican told The Washington Times. “Most people in the caucus are for having a balanced budget amendment to the Constitution, but they don’t want to crunch the numbers necessarily. I think they know when you crunch the numbers that even if you eliminate all the non-military spending, you’re still short.”

Thanks in large part to the wars in Iraq and Afghanistan, defense spending has ballooned since 2000, jumping from $294 billion to roughly $700 billion a year, or 20 percent of the entire federal budget. And, generally speaking over that time, lawmakers have grown accustomed to giving the Pentagon whatever it wants for fear of being called weak on defense.

“At the end of the day, even when you take out the cost of the wars, military spending in the base budget has grown close to $1 trillion since 2000,” said Christopher A. Preble, director of foreign-policy studies at the libertarian-leaning Cato Institute. “So, I think there is kind of a growing realization that the cost that we have incurred on behalf of a lot of other places around the world are growing increasingly burdensome, and the military has not exactly been starved of funds.”

After the November election, there appeared to be a growing sense that defense spending was going to have to be on the table to get the nation’s fiscal house in order, as voters vented anxiety over the nation’s trillion-dollar deficits and more than $14 trillion national debt.

The narrative spilled over into December, when the president’s high-profile deficit-reduction commission released a well-received set of recommendations.

“Defense has to be on the table; that’s obvious,” said then-Sen. Judd Gregg, a commission member. “We looked hard a defense and made a suggested top-line number, and then listed a large number of specific cuts that would accomplish the top line.”

But months later, none of the key players has offered up specifics.

House Republicans and Senate Democrats have approved stopgap spending bills that avoid military cuts. President Obama, meanwhile, offered up a 2012 spending plan that only cuts projected military-spending growth. He’s also specifically cited the underfunding of the military as a reason to veto House spending bills.

Recent military action in Libya only complicates the situation further, as the administration hasn’t provided any estimate for the related costs, leaving some lawmakers fearful that it will grow to eat up at least some of the savings that they’ve worked to pass in recent months.

While the move won’t break the bank, Mr. Preble said that U.S. involvement in the North African nation is another example of why lawmakers and military leaders need to rethink the role the U.S. military plays across the globe.

“It’s not the waste. Its not the inefficiency” that’s driving up the defense spending, Mr. Preble said. “We spend too much because we use our military too much.”

The sentiment is catching on with some Republicans. During a recent appearance in Iowa, Mississippi Gov. Haley Barbour, a likely candidate for the Republican presidential nomination in 2012, said that the GOP won’t have any credibility on spending if they are not willing to tackle the defense budget.

Whatever the case, Mr. Paul said eventually lawmakers are going to have to face the “inconvenient truth” that “we will have to cut military spending if we are really in favor of balancing the budget.”

“That’s something that conservatives will have to overcome, because many think that every military dollar is sacred, that every military dollar is for national defense, and really in the end we have to acknowledge that military spending has doubled in the last 10 years, and we simply can’t balance the budget by cutting non-military spending.”